The present invention relates to a cable drum for the automatic rewinding of cables.
Many devices require for rational use a continuously varying cable length. This applies to telephone sets with their wires or devices connected to the public power line which are used flexibly. If they are provided with the maximum cable length needed, there frequently arises the problem that with shorter distances between outlet and device, the cable tends to become twisted. In addition, there is danger that the cable lying on the floor might be damaged. Therefore it is useful to wind up the superfluous cable lengths on a cable drum. Particularly simple handling of a cable can be achieved by having the cable not required to be automatically wound on the cable drum.
There is already known in the art a cable drum for the automatic rewinding of a cable where two separate winding areas, located on a shaft loaded with a return spring, and a slot, fixing the cable in the winding areas, are provided in the disc-shaped separating wall common to the winding areas. The return spring acts relative to an axis passing through the shaft; this axis is provided on the shaft outside with two wire loops to guide the cable to be wound. In order to insert the cable, the return spring must be preloaded by suitably rotating the shaft relative to the wire loops. Only then can the cable be inserted in the slot of the disc-shaped separating wall of the winding areas, and be wound with slow release of the shaft in two wound packages.
The known cable drum has various disadvantages. Insertion of the cable requires considerable manual dexterity since the return spring must first be pre-loaded and then slowly released after fixing the cable in the winding areas. If the return spring has not been sufficiently preloaded, the cable is not completely wound up and there is danger that windings of the cable package slip out of the winding areas. This may block the cable drum and, in the extreme case, destroy (damage) the cable. In addition, the known cable drum can be rationally used only for small cable lengths, since otherwise the preloading of the return spring by hand becomes unreasonable or even impossible due to the increasing spring force.
It is, therefore, an object of the present invention to provide, while avoiding the above disadvantages, a cable drum for the automatic rewinding of a cable to be installed without special skill by laymen on a cable. The cable drum is adapted to cables of great lengths and still reliably protects the cable in the wound state against damage or sliding-off of the cable wound packages. In addition, quick replacement by other cable drums is to be possible.
Another object of the present invention is to provide an arrangement of the foregoing character which is substantially simple in construction and may be economically fabricated.
A further object of the present invention is to provide a cable drum, as described, which may be readily maintained in service and which has a substantially long operating life.